The present invention relates to preparing tissue samples for pathological study, particularly to a microfabricated instrument for tissue biopsy and analysis, and more particularly to a microfabricated biopsy/histology system using a combined tissue cutter and specimen treatment chamber, thus minimizing specimen handling.
The process of preparing tissue samples for pathological study, known as histology, requires skill and experience. The current process used for preparing samples for histological analysis is labor intensive, somewhat of an art form, and requires expensive equipment and large quantities of chemicals. In the traditional process, a piece of tissue is embedded in paraffin wax, and thin ribbons are sliced off using a microtome, then mounted onto glass slides, treated with chemicals, and viewed with a microscope. Large quantities of chemicals are required to fix, dehydrate, and stain the tissue. In addition, the large tissue samples removed from a patient causes substantial discomfort.
Recently, micro-biopsy tools have been developed to enable removing only a small amount of tissue or other material in a minimally invasive manner, and reduce risks, costs, injury, and patient discomfort associated with traditional biopsy procedures. Such micro-biopsy tools are described and claimed in copending U.S. application Ser. No. 08/887,780 filed Jul. 3, 1997 entitled "Micro-biopsy/Precision Cutting Devices", now U.S. Pat. No. 5,928,161 assigned to the same assignee. These micro-biopsy tools are formed from silicon and anisotropic etching of silicon, resulting in extremely sharp edges, ideally suited for slicing soft tissues.
The present invention significantly simplifies specimen slicing and subsequent chemical treatment, and combines these operations into one complete histology instrument. The sample is sliced to a precise thickness with a micromachined silicon cutter, trapped in a chamber such that the sample lies flat against a glass surface, treated with appropriate chemicals, and viewed through the glass, all without directly handling the specimen after it has been sliced. The system of this invention may be used to slice and process fresh tissue samples or samples embedded in paraffin wax. The system of this invention has three components: a cutter for directly performing a microbiopsy or slicing a thin section from previously biopsied tissue, and specimen chamber for capturing, treating, and viewing the thin cut section, and flow channels for exposing the specimen to a variety of chemicals. The cutter is formed by anisotropic etching of silicon and enables slicing very thin specimens (about 2 .mu.m or greater).